/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xalan.transformer;

import javax.xml.transform.TransformerException;

import wx.xml.xalan.xalan.templates.ElemNumber;
import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xpath.NodeSetDTM;
import wx.xml.xalan.xpath.XPathContext;

/**
 * A class that does incremental counting for support of xsl:number.
 * This class stores a cache of counted nodes (m_countNodes).
 * It tries to cache the counted nodes in document order...
 * the node count is based on its position in the cache list
 *
 * @xsl.usage internal
 */
public class Counter {

    /**
     * Set the maximum ammount the m_countNodes list can
     * grow to.
     */
    static final int MAXCOUNTNODES = 500;

    /**
     * The start count from where m_countNodes counts
     * from.  In other words, the count of a given node
     * in the m_countNodes vector is node position +
     * m_countNodesStartCount.
     */
    int m_countNodesStartCount = 0;

    /**
     * A vector of all nodes counted so far.
     */
    NodeSetDTM m_countNodes;

    /**
     * The node from where the counting starts.  This is needed to
     * find a counter if the node being counted is not immediatly
     * found in the m_countNodes vector.
     */
    int m_fromNode = DTM.NULL;

    /**
     * The owning xsl:number element.
     */
    ElemNumber m_numberElem;

    /**
     * Value to store result of last getCount call, for benifit
     * of returning val from CountersTable.getCounterByCounted,
     * who calls getCount.
     */
    int m_countResult;

    /**
     * Construct a counter object.
     *
     * @param numberElem The owning xsl:number element.
     * @param countNodes A vector of all nodes counted so far.
     * @throws TransformerException
     */
    Counter(ElemNumber numberElem, NodeSetDTM countNodes) throws TransformerException {
        m_countNodes = countNodes;
        m_numberElem = numberElem;
    }

    /**
     * Construct a counter object.
     *
     * @param numberElem The owning xsl:number element.
     *
     * @throws TransformerException
     *
    Counter(ElemNumber numberElem) throws TransformerException
    {
    m_numberElem = numberElem;
    }*/

    /**
     * Try and find a node that was previously counted. If found,
     * return a positive integer that corresponds to the count.
     *
     * @param support The XPath context to use
     * @param node    The node to be counted.
     * @return The count of the node, or -1 if not found.
     */
    int getPreviouslyCounted(XPathContext support, int node) {

        int n = m_countNodes.size();

        m_countResult = 0;

        for (int i = n - 1; i >= 0; i--) {
            int countedNode = m_countNodes.elementAt(i);

            if (node == countedNode) {

                // Since the list is in backwards order, the count is
                // how many are in the rest of the list.
                m_countResult = i + 1 + m_countNodesStartCount;

                break;
            }

            DTM dtm = support.getDTM(countedNode);

            // Try to see if the given node falls after the counted node...
            // if it does, don't keep searching backwards.
            if (dtm.isNodeAfter(countedNode, node))
                break;
        }

        return m_countResult;
    }

    /**
     * Get the last node in the list.
     *
     * @return the last node in the list.
     */
    int getLast() {

        int size = m_countNodes.size();

        return (size > 0) ? m_countNodes.elementAt(size - 1) : DTM.NULL;
    }
}
